A new radio front end architecture is needed to support a world phone or world tablet type user equipment that is required to operate in a carrier aggregation mode for many band combinations. For example, the radio of a world phone or world tablet is required to support band 7 (B7) of Long-Term Evolution Frequency Division Duplex (LTE FDD) along with bands B38, B40, B41, and B41 Extended Global Platform (XGP) LTE Time Division Duplex (TDD), which covers a bandwidth that ranges from 2300 MHz to 2700 MHz.
There are numerous LTE TDD bands within the bandwidth that ranges from 2300 MHz to 2700 MHz. As a result, a relatively large number of separate transmit filters and receive filters are needed. For example, the transmit filters are used to prevent spurious noise from being transmitted into receivers that are tuned to frequencies within an industrial, scientific, and medical (ISM) band. A world phone or world tablet user equipment will typically include several receivers for the ISM band. Typically, the receivers will be dedicated to wireless data technologies such as wireless fidelity (Wi-Fi) and Bluetooth.
The receive filters are typically used to protect against the ISM transmit signals inside the same user equipment. The ISM transmit signals can have power levels as high as +10 dBm. Moreover, the RX filters must protect against external blocker levels that exist due to base transmitter stations (BTS), television (TV) stations, etc.
In one particular example, bands B38 and B41 XGP require separate receive filters for a main reception while also requiring a separate transmit filter. Moreover, a diversity or receive multiple input multiple output (MIMO) path requires separate receive filters for each band that is allocated for diversity reception. As a result of this relatively large number of receive and transmit filters, along with an increased number of switch throws, an undesirable increase in insertion loss will occur. For example, each switch throw typically adds around 0.08 dB of insertion loss for the relatively high frequencies that range from 2300 MHz to 2700 MHz.
Thus, there is a need for a new radio front end architecture that is configured to rearrange LTE TDD band filtering such that the number of receive filters and transmit filters needed is reduced. Benefits of the new radio front end architecture include a reduced number of switch throws and reduced insertion loss.